It is well understood that in the use of printer devices of the kind that are commonly used to provide printout information for electronic data processing systems, it is necessary to employ different thicknesses of paper for the printout reports. For instance it is a common practice to provide a printout report which is made up of a plurality of carbon copies and therefore the total form package which is being passed through the printer, to have the report printed thereon, is composed of a number of sheets as well as the carbon paper, and this package actually becomes relatively thick. When such a thick package is used it is important to provide a gap which is sufficiently wide to enable the report, or the package of blank pages, to be transported without being jammed either between the type hammers and the ribbon or between the ribbon and the backup plate or platen. If we consider a system where the paper is pushed by the type hammers against the type font (which may be on either a drum or a movable band or the like) then it should be understood that the hammer stroke be as consistent for a package of forms, as for a single sheet, and that the forms be held close to the hammers whether the hammers are striking a single sheet or a package of sheets.
The necessity for adjusting the gap between the print hammers and the type font (for the moment not being concerned that the ribbon lies therebetween) has long been recognized and there have been many solutions offered to accommodate this need.
For instance in one prior art arrangement the print drum is moved away from the hammer assembly and stop lugs are positioned further into or further out of the housing means so that when the print drum is set back in its printing position it is literally held further away or held closer to the print hammers. In this particular prior art arrangement the individual setting of the lugs can be critical in that they cannot cause a skew in the type font device and further the scheme necessiates unlocking and lifting out of the entire printing mechanism. In another prior art device the print drum mechanism is made pivotable at one location and a cam member is disposed to pivot the frame so that the print drum is moved away from the actuating hammers.
The present device accomplishes the misson of making the gap between the type font faces and the print hammers variable and accomplishes that misson with simplicity and with less complex hardware than was heretofore employed.